2 What is photosynthesis? Write a sentence or two to describe what photosynthesis is. Use thekeywords: light energy, carbon dioxide, water, oxygen, chlorophyll,chemical energy, photosynthesis.Plants use photosynthesis to convert carbon dioxide and water,in the presence of chlorophyll and light energy, to make glucose andoxygen. Photosynthesis is important in converting light energy tochemical energy.
3 carbon dioxide + water glucose + oxygen 6CO2 6H20 C6H12O6 602 Photosynthesis is an important process because it converts light energy to chemical energy, which is stored in glucose. The chemical energy is released when glucose is broken down during respiration.lightchlorophyll
7 Exam question(c) The leaves produce glucose by photosynthesis. (i) Write the word equation for photosynthesis (2) (ii) Describe how the structure of the leaf is adapted to help obtain the gas required for photosynthesis (2)
8 Exam question(c) The leaves produce glucose by photosynthesis. (i) Write the word equation for photosynthesis. carbon dioxide + water glucose + oxygen (2) (ii) Describe how the structure of the leaf is adapted to help obtain the gas required for photosynthesis. thin; large surface area; stomata; air spaces / spongy (mesophyll); (2)
9 How can we test that photosynthesis has occurred in plants? What is the evidence for photosynthesis?How can we test for starch?
10 How can we test that photosynthesis is occurring in plants? Presence/ absence of lightoxygen given offHow can we test that photosynthesis is occurring in plants?Presence/absenceof CO2starch producedPresence / absence of chlorophyll
15 3. ChlorophyllPredict the results of the starch test.Take a variegated plant which has been under bright light for 24hours and remove one of the leaves.Make a sketch of the leaf showing approximately where the green and non green areas are.
16 Testing Leaves for Starch Dunk the leaf in a 90oC water bath using forceps until it is soft (2 minutes).Transfer leaf to a boiling tube of ethanol and place in 90oC water bath until the leaf turns white (5 minutes).Wash the leaf in water.Place the leaf on a Petri dish and flood with iodine solution.
17 Starch Test (diagrams) ResultsWrite up results and include diagrams.ConditionTreatmentStarch Test (diagrams)BeforeAfterLightCarbon dioxideChlorophyll
18 Conclusions What do your results tell you about photosynthesis and … a. light?b. carbon dioxide?c. chlorophyll?What was the control for each experiment?It is difficult to set up an experiment to prove that water is needed for photosynthesis. Explain why it is difficult.
19 Light and starch production Take a finely sliced piece of potato and place on a glass slideadd two drops of iodine solution and place a coverslip on topview under the microscope.What can you see?summary